* {
  border: 0;
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --hue: 223;
  --bg: hsl(var(--hue),10%,90%);
  --fg: hsl(var(--hue),10%,10%);
  --primary: hsl(var(--hue),90%,30%);
  --trans-dur: 0.3s;
  --trans-timing: cubic-bezier(0.65,0,0.35,1);
  font-size: calc(16px + (48 - 16) * (100vw - 280px) / (3840 - 280));
}

body,
button {
  font: 1em/1.5 "DM Sans", sans-serif;
}

body {
  background-color: var(--bg);
  color: var(--fg);
  display: flex;
  height: 100vh;
}

form {
  container: form/inline-size;
  margin: auto;
  padding: 1.5em;
  width: 100%;
  max-width: 36em;
}

.btn {
  background-color: var(--primary);
  border-radius: 0.25em;
  color: white;
  cursor: pointer;
  display: block;
  padding: 0.375em 0.75em;
  transition: background-color var(--trans-dur) var(--trans-timing), opacity var(--trans-dur) var(--trans-timing);
  width: 100%;
  -webkit-appearance: none;
  appearance: none;
  -webkit-tap-highlight-color: transparent;
}
.btn:disabled {
  cursor: not-allowed;
  opacity: 0.5;
}
.btn:not(:disabled):hover {
  background: hsl(var(--hue), 90%, 10%);
}
.btn-group {
  display: flex;
  justify-content: center;
  gap: 0.75em;
  margin-top: 1.5em;
}

.steps {
  background-color: white;
  border-radius: 0.75em;
  display: flex;
  padding: 1.5em;
  flex-direction: column;
  justify-content: center;
  width: 100%;
}
.steps__connector, .steps__step {
  position: relative;
}
.steps__connector {
  background-color: hsl(var(--hue), 10%, 80%);
  margin-inline-start: 0.75em;
  width: 0.125em;
  height: 1.25em;
  transform: translateX(-50%);
  transition: background-color var(--trans-dur);
}
.steps__connector:before {
  background-color: var(--primary);
  content: "";
  display: block;
  width: 100%;
  height: 100%;
  transform: scale(1, 0);
  transform-origin: 50% 0;
  transition: background-color var(--trans-dur), transform var(--trans-dur) var(--trans-timing);
}
.steps__step {
  display: flex;
  align-items: center;
  flex-shrink: 0;
  z-index: 1;
}
.steps__step-name {
  color: hsl(var(--hue), 10%, 50%);
  font-size: 0.75em;
  line-height: 2;
  transition: color var(--trans-dur) var(--trans-timing), font-weight var(--trans-dur) var(--trans-timing);
}
.steps__step-number {
  background-color: hsl(var(--hue), 10%, 80%);
  color: white;
  border-radius: 50%;
  margin-inline-end: 0.5em;
  text-align: center;
  width: 1.5em;
  height: 1.5em;
  transition: background-color var(--trans-dur) var(--trans-timing), box-shadow var(--trans-dur) var(--trans-timing);
}
.steps__step--current .steps__step-name, .steps__step--done .steps__step-name {
  color: hsl(var(--hue), 10%, 10%);
  font-weight: 700;
}
.steps__step--current .steps__step-number, .steps__step--done .steps__step-number {
  background-color: var(--primary);
}
.steps__step--current .steps__step-number, .steps__step--current .steps__step-name {
  transition-delay: var(--trans-dur);
}
.steps__step--current .steps__step-number {
  box-shadow: 0 0 0 0.125em hsla(var(--hue), 90%, 30%, 0.4);
}
.steps__step--done + .steps__connector:before {
  transform: scale(1, 1);
}

/* Change layout depending on form width */
@container form (min-width: 30em) {
  .btn {
    width: auto;
  }

  .steps {
    flex-direction: row;
    align-items: center;
    padding: 1.5em 2.25em 2.25em 2.25em;
  }
  .steps__connector {
    margin-inline-start: 0;
    width: 100%;
    height: 0.125em;
    transform: translateY(-50%);
  }
  .steps__connector:before {
    transform: scale(0, 1);
    transform-origin: 0 50%;
  }
  [dir=rtl] .steps__connector:before {
    transform-origin: 100% 50%;
  }
  .steps__step-name {
    position: absolute;
    top: 100%;
    left: 50%;
    text-align: center;
    width: 6em;
    transform: translateX(-50%);
  }
  .steps__step-number {
    margin-inline-end: 0;
  }
}
/* Dark theme */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: hsl(var(--hue),10%,10%);
    --fg: hsl(var(--hue),10%,90%);
    --primary: hsl(var(--hue),90%,70%);
  }

  .btn {
    color: hsl(var(--hue), 10%, 10%);
  }
  .btn:not(:disabled):hover {
    background: hsl(var(--hue), 90%, 50%);
  }

  .steps {
    background-color: hsl(var(--hue), 10%, 20%);
  }
  .steps__connector {
    background-color: hsl(var(--hue), 10%, 40%);
  }
  .steps__step-name {
    color: hsl(var(--hue), 10%, 50%);
  }
  .steps__step-number {
    background-color: hsl(var(--hue), 10%, 40%);
    color: hsl(var(--hue), 10%, 20%);
  }
  .steps__step--current .steps__step-name, .steps__step--done .steps__step-name {
    color: hsl(var(--hue), 10%, 90%);
  }
  .steps__step--current .steps__step-number {
    box-shadow: 0 0 0 0.125em hsla(var(--hue), 90%, 70%, 0.4);
  }
}